After Poirot pays a routine visit to his dentist, the doctor apparently shoots himself to death a short time later. Chief Inspector Japp appropriately recruits the detective as both witness and consultant.

While Poirot sleeps on an airplane flight from Paris to London, a notorious French moneylender is murdered with a poisoned dart.

Poirot receives taunting letters from a serial killer who appears to choose his victims and crime scenes alphabetically.